This article highlights the need for a clearer conceptual appreciation of the relationships among and between predictors and criteria, and for a better understanding of measurement issues in selection. A process model of selection is outlined that includes recent research on the changing relationships of ability to performance at different stages of skill acquisition, the interaction between type of task and validity, the role of motivational constructs in the measurement and validation process, and the reciprocally interacting influences of work experience and individual characteristics. Comment is offered on issues such as general versus specific abilities, the ‘big five’in personality, aptitude by treatment or training interactions and maximal versus typical performance. Measurement issues are discussed throughout, but particularly in relation to the assessment proc